1. Field of the Invention
The present invention relates to a transaxle including a hydrostatic transmission (hereinafter, “HST”) and an axle driven by the HST. Especially, the transaxle serves as one of right and left transaxles carrying respective right and left individual axles for driving a zero-turn vehicle, e.g., a lawn mower.
2. Related Art
As disclosed by U.S. Pat. No. 6,125,630 A (hereinafter, '630), there is a well-known conventional hydraulic transaxle serving as one of right and left transaxles carrying respective right and left individual axles for driving a zero-turn vehicle, e.g., a lawn mower. The transaxle includes an HST, an axle, and a reduction gear train for transmitting power from the HST to the axle. The transaxle includes a transaxle casing incorporating the HST and the reduction gear train and supporting the axle. The HST includes a hydraulic pump for receiving power from a prime mover, a hydraulic motor for outputting power to the reduction train, and a center section on which the hydraulic pump and the hydraulic motor are mounted to be fluidly connected to each other via a hydraulic fluid circuit formed in the center section.
'630 discloses some transaxles adaptable as one of right and left transaxles for a zero-turn vehicle. One transaxle disclosed by '630 (see FIG. 5) includes an HST configured so that the hydraulic pump has a vertical pump shaft, and the hydraulic motor has a horizontal motor shaft extended parallel to the horizontal axle. All gears of the reduction gear train drivingly connecting the motor shaft to the axle are spur gears. The transaxle is provided with a brake system including a brake disc, a brake camshaft, and a brake shoe. The brake disc is disposed vertically on the motor shaft, and the brake camshaft is extended vertically adjacent to the brake disc. By rotating a brake operation arm fixed on the brake camshaft, the brake camshaft is rotated to press the brake shoe against the brake disc, thereby braking the motor shaft, the reduction gear train, and the axle. This transaxle having the horizontal motor shaft parallel to the axle expands in the axial direction of the axle and increases the lateral dimension of its transaxle casing, thereby being an obstacle to facilities for mounting this transaxle on a vehicle.
Another transaxle disclosed by '630 (see FIGS. 21 and 22) includes an HST having a horizontal motor shaft extended perpendicular to the axle. Bevel gears are used to drivingly connect the motor shaft to the axle. This transaxle is advantageous to reduce the lateral dimension of its transaxle casing. However, the transaxle casing has a great fore-and-aft dimension so that the pump shaft becomes distant from the axle, thereby also being an obstacle to facilities for mounting this transaxle on a vehicle.
Further, the transaxle needs a compact brake system that can efficiently brake the motor shaft, the reduction gear train, or the axle.